Ah... they connect comb size to bone mass and comb size to egg laying. Leghorn hens are some of th highest layers ever but other "pea combed" hens are very very good as well.

The pea comb or flat comb are inherited traits. Breeds like Leghorns that lay a lot of eggs are skinny, thin birds. Many pea combed chickens are heavier breeds, who often lay less but grow much larger and put on more muscle. Cornish, that are crossed (usually with White Rocks) for our eight-month-old fryers have small combs but huge, blocky bodies.

In any case, it makes far more sense to me that roosters deliver more sperm to visibly fertile hens than to pullets (young hens) or hens just starting to lay for the season, and that this accounts for more "investment" in the hens with larger combs, than to think that the hen lays *more* eggs and that's why her genes get passed along.